The early ultramicroscopic changes occurring in the various corneal layers of experimental allografts have been studied. Eight publications in collaboration with G.K. Smelser, H. Inomata and A. Kanai describe these studies. At the present time we are conducting experiments to study cell changes in tissue culture when exposed to sensitized lymphocytes. A summary of work in progress is enclosed. This grant has supported the studies reported in over thirty papers concerning clinical and pathological changes in the cornea. Specific studies in the area of graft failure and graft rejection have also been reported in the enclosed list of publications. Availability of clinical material in this institution facilitates the progress of our studies.